This section introduces aspects that may help facilitate a better understanding of the inventions. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is prior art or what is not prior art.
A message authentication code (referred to herein as a MAC, MAC tag, or tag) is a digital signal sequence used for authenticating a message exchanged between a sender and receiver each having a shared secret “key”. In a typical MAC authentication scenario, the sender of a message runs it through a cryptographic function (e.g., a function following the Advanced Encryption Standard) having the message and the secret key as inputs, yielding a MAC tag as an output. The sender then sends the message and the tag to the receiver. The receiver runs the received message through the same MAC algorithm using the same key, yielding a second MAC tag. The receiver then compares the tag generated by itself to the tag received from the sender and if they are the same, the message is deemed authentic. If they are not the same, it is an indication that the message was altered or compromised in some manner during the exchange. Often, the MAC can represent a significant information overhead, in some cases being larger in size (e.g., 128 bits) as compared to the size of the message that it authenticates (e.g., on the order of 10-15 bits).